I made a German Pils with some ideas from this study. The yeast had to be built up to get the right pitch. So as mentioned in the previous post, I made a 2 liter 1.018 starter with 8-10 grams of Fermaid O. I used a defusion stone and aerated with pure oxygen for 90-120 seconds. I let it spin for 12-14 hours and then stop the stir plate and let the yeast stay at room temperature for another 10-12 hours. After 24 hours total, it was crashed cooled for another 24 hours.
I then decanted the yeast from the first starter and pitched it into another 4 liter starter. I used the same method as above, the only difference was this next step was at 1.036. I then crashed cooled it and waited 2 days for brew day.
The yeast I built up was @ 2 months old, so I wasn't sure what to expect. I pitched it at 48F (8.9C) and let it free rise to 52F (11.1C). The lag time was one of the shortest I have ever had at that temperature, @15 hours. Typically from that yeast (Wyeast 2124) I would expect 18 -22 hours. The fermentation started before the beer could come up to 52F. The other thing I noticed was that there was little or no sulfur during the entire fermentation, typically I would get this foul odor @ 2-3 days into the fermentation.
The beer hit terminal gravity about 1-2 days earlier than previous batches and the AA was just above 80%. I would normally see 78-79%, so not a big difference, but still an improvement. The beer itself is very good, very clean and well attenuated, delicious actually. I hope to get it into a competition in late January to see how well it does. So far I can see where this is an improvement over my past beers.
I brewed another beer using this same starter technique this weekend. I used fresh 2124 this time and brewed a Helles. The lag time was incredibly short, 10 hours at 47-48F (8.5C). This one is presently churning away at 51F (10.5C), and is producing some sulfur, but still less than what I normally see.
I think the addition of FAN in the form of Fermaid-O is producing healthy yeast in higher yeast counts that have excellent vitality. I don't believe that it is practical or necessary to get the yeast into a aerobic state to produce very healthy yeast. To me the main take away is to get the yeast the proper nutrients for growth (FAN) and build up their sterol/lipids reserves (oxygen) to able to thrive in a less than ideal environment of fermenting beer. Now I want to know if I can reduce the amount of yeast extract and still see the same results.
Thanks again Mark for bringing this to the forum, it's been a great lesson in yeast health and biology.
